Quickly adjustable vise having a nonrotatable spindle axially advanced by a split-nut mechanism



H. C. CHASE Jan. 10, 1961 2,96 7,445 SPINDLE SM QUICKLY ADJUSTABLE VISE HAVING A NONROTATABLE AXIALLY ADVANCED BY A SPLIT-NUT MECHANI Filed Oct. 22, 1956 2 Sheets-Sheet 2 United States Patent QUICKLY ADJUSTABLE VISE HAVING A. NON- ROTATABLE SPINDLE AXIALLY ADVANCED BY A SPLIT-NUT MECHANISM Hamilton C. Chase, La Habra, Califi, assiguor to Julian A. Monax, Los Angeles, Calif.

Filed Oct. 22, 1956, Ser. No. 617,536

8 Claims. (Cl. 81-36) This invention relates generally to tools and relates more particularly to quick-adjusting mechanisms.

While the invention has particular utility in connection with vises for holding work and is shown and described in such connection, it is to be understood that its utility is not confined thereto.

Vises of this character have a stationary jaw and a movable jaw moved or actuated by means of a rotatable driving screw or the like, and considerable time is lost in adjusting the movable jaw by means of such screw so as to hold the work. It is, therefore, an object of the present invention to provide a vise having means for quickly releasing the movable jaw from its operative connection with the screw so that said jaw may be easily and quickly adjusted to engage the work to be held by the vise and for quickly tightening said jaws on the work.

It is another object of the invention to provide a footactuated means for quickly releasing the movable jaw from operative engagement with said screw. In the present arrangement the screw is non-rotatable and is carried by the movable jaw, there being a rotatable clutch mechanism which provides a driving connection between said screw and movable jaw, said clutch mechanism including a plurality of radially movable segments having helical teeth engageable with said screw so that when the clutch mechanism is rotated the movable jaw will be actuated, said segments being releasable from the screw to release said jaw so that it may be quickly and easily adjusted toward and from the fixed jaw.

Still another object of the invention is to provide means for automatically effecting engagement of the teeth of the segments with the threads of said screw and positively holding said segments in the screw-engaging position.

A further object of the invention is to provide means actuated by the operators foot for tightening the vise jaws to thereby securely hold the work, there being a clutch in the foot-actuated mechanism to effect rotation of nut segments on an axially movable screw for tightening the vise when the segments of the jaw-driving clutch are in mesh with the threads of said screw.

A still further object of the invention is to provide mechanism of this character that is relatively simple and sturdy in construction, and efiective and reliable in operation.

Another object of the invention is to provide mechanism of this character that is relatively inexpensive to manufacture.

The characteristics and advantages of the invention are further sufliciently referred to in connection with the following detailed description of the accompanying drawings which represent a preferred embodiment. After considering this example skilled persons Will understand that variations may be made without departing from the principle disclosed, and it is contemplated that any structures, arrangements or modes of operation that are properly within the scope of the appended claims may be employed.

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Referring to the drawings:

Fig. 1 is a side view of mechanism or apparatus em bodying the present invention.

Fig. 2 is an enlarged longitudinal section through the vise.

Fig. 3 is an .enlarged longitudinal section of the clutch mechanism with the parts in the released position.

Fig. 4 is an enlarged sectional view taken on line 44 of Fig. 2.

Fig. 5 is an enlarged sectional view taken on line 5-5 of Fig. 2.

. Fig. 6 is an enlarged sectional view taken on line 6-6 of Fig. 2.

Fig. 7 is an enlarged sectional view taken on line 7-7 of Fig. 2.

Fig. 8 is an enlarged sectional view taken on line 8-8 of Fig. 2.

Fig. 9 is an enlarged side view of a portion of the footactuated mechanism for effecting release of the movable jaw of the vise.

Fig. 10 is a side view of the split-nut body and releasing sleeve of the release mechanism.

Referring to Fig. 1 there is shown a vise, indicated generally at 15, secured to a bench 16, or the like, by means of screws 17 received in openings provided therefor in flanges 18.

The vise comprises a fixed jaw 19 having a rearwardly extending hollow portion or housing 20 which is open at the bottom and which has a rear end wall 21. At the forward end of the fixed jaw is a vertical or transverse wall 22 having an opening 23 therein below which is a bearing 24 which projects forwardly of said wall 22. The rear wall 21 of the fixed jaw is provided with an opening 25 aligned with the opening 23 for slidable reception of a horizontal body 26 of a movable jaw, indicated generally at 27. The lower side of the body 26 rests and slides upon the upper surface of the bearing 24. The body 26 is hollow and at the forward end there is an upturned portion 28 carrying a face-plate 29 at the upper rear part for cooperation with a faceplate 30 carried by the fixed jaw member. A rear wall 32 of the movable jaw is provided with a tapped opening 33 for reception of a screw 34 received in an opening provided therefor in a screw-anchoring plate 35 which depends below the underside of the body of the movable jaw. The anchor plate 35 is provided with a generally square opening 37 for reception of an end portion 38 of a screw 39, the end portion 38 being of similar crosssectional shape as the opening 37 so that the screw is held against rotation relative to the anchor plate 35. The rear of the screw is provided with a threaded end portion on which are received a pair of lock nuts 40 to thereby hold the screw in position. The screw 39 extends forwardly of the anchor plate in spaced relation to the underside of the body 26 of the movable jaw and parallel thereto, said screw extending into the hollow housing portion 20 of the fixed jaw through an opening 42 provided therefor in the wall 21 of said housing.

There is means within the housing 20 for moving the screw longitudinally and said means comprises a tubular shaft 43 rotatably mounted in an opening provided therefor in the wall 22 of the fixed jaw and a support member 44 disposed within the housing 20 and secured thereto in rearwardly spaced relationship to the wall 22. At the rear or inner end of the shaft 43 there is a thrust washer 46 disposed against the rear side of the support member 44 and behind said washer is a cylindrical split-nut body 47 having a recess at the forward end thereof for reception of the rear end portion of shaft 43, there being a rear end wall 48 of said body which abuts against the rear end of the shaft 43 and said body has an inwardly pro- 3 jecting key 49 slidable in a key slot 50 extending longitudinally in the outer surface" of the shaft 43 so that the body and shaft will rotate together. The 'bodycarr'ies a release sleeve 51 having anaxial bore47a said sleeve being slidable on said body and b'ei'ngsecnred'theret'o'by means or a set screw 52 screwed into a tapped recess provided therefor in the body 47 and having its outer end portion disposed in a slot53 insaidrel'easesleeve. With this arrangement the release sleeve is' s lidable*longi-' tudinally on the body 47 bu is "held'against rotation thereon. At therear the release sleeve is interiorlyen larged as at 54 and there 'is an annular cam surface 56 which extends between the rear end of bore 47a of the' sleeve and theenlarge'd diameter portion' 54; the purpose of said cam 56 beinghereinafter described. Therear end or the release sleeve is closed by a plate 58having a plurality of openings therein in which are fixedthe"re-' duced-in-diamet'er rear end portion of respective release pins 59 which extend forwardly of the plate 58 into the sleeve'Sl and have pointed forward ends 60.

The body 47 has a plurality of'longrtudinally extend ing openings 66 at the inner or rear end in which the release pins 59 are slidably received, it being noted that said pins are at all times received within said openings 66 so that the body 47 and release sleeve 51 are held against relative rotation with respect to each other. 'It is'als'o to be noted thatthe plate 58 has an axial opening through which the screw 39 extends and said body, 47 h'a's'ii similar "opening therethrough in register with the opening in plate 58 for reception of said screw .Which is adapted to freely move longitudinally in said openings. Intermediate its ends the body 47 is provided with a plurality of radially extending openings, square in cross section, there being four of said openings annularly spaced at 90-degree intervals. In each of said openings there is a nut segment 68 slidable radially inwardly and outwardly. The inner ends of said segments are provided with portions of internal threads 69 which match lefthand threads of the screw 39 and are meshable there.- with. At the rear of each segment is a recess 70 in which a pointed forward end 60 of one of the release pins 59 is receivable. It is to be noted in Fig; 2 that when the release sleeve 51 is at its rearward position the pins 59 are withdrawn from the recesses 70 so that the threaded portions of the segments are in engagement with the threads of the screw 39 and are positively'held in such position by the forward end portion of said sleeve." Also, when the segments 68 are thus engaged with the screw 39, the outer parts of the recesses 70 are spaced slightly outwardly of the points at the forward ends of the pins 59 so that said pins may enter said recesseswhen the sleeve 51 is moved forwardly to effect outward movement of the segments as shown in Fig. 3 to thereby disengage the threaded portion '69 of 'said segments firom' the threads of the screw 39. It is to be noted that when the release sleeve 51 is moved rearwardlyfrorn the position shown in Fig. 3 the cam surface 56'engages a similar cam surface at the forward ends of the segments and forces said segments inwardly as said sleeve is moved rearwardly.

At the forward side of the support member 44 there is a holding ratchet 75 having an anchor pin 76 secured in an opening provided therefor in the ratchet 75 adjacent the periphery thereof. The pin 76 is adapted to engage a flattened portion 77 of the support member, said flattened portion 77 being disposed at the bottom of said member. The pin prevents rotation of the ratchet 75 with respect to the support member 44 but permits rotation of the shaft 43 within said ratchet. Forwardly of the ratchet 75 is a drive ring 80 havingan axialopening "therein .50 that'said drive ring 80 is slidable along the shaft43. ,Ihedrive ring is provided with a key 81 (Fig. 7 )i dabl n .theew w Sti t e 443 s that. the drive ring 80 and shaft 43 will rotate together.

The drive ring 80 is provided with a plurality of longitudinally extending annularly spaced recesses 82 in the rear face thereof. Openings82 face the holding ratchet and each opening is provided with a pawl 84 slidable in the opening and having an outwardly extending tooth 85 with a trailing shoulder 87 and a leading cam face 86. The pawls are provided with axial recesses at their inner ends for reception of-springs SS-forurgin'g-said pawls outwar'dly toward the holding ratchet 75 so that the teeth 85 of said pawls will e'rigage teeth 90 on the adjacent face of"the holding"ratchet"-75. *This "pawl-a'nd-ratchet ar-" rangement prevents the shaft 43 from moving in a reverse direction when the vise is being tightened and thereby holds the jaws" in thetightened position; Itis to be noted that the pawls are so arranged that'the leading cam faces of the teeth thereof will slide over the teeth 90 of the ratchet 75 when the ring 80 is rotated counterclockwise, as indicated by an arrow in Fig. 7, but the trailing shoulders 87 of said pawl will engage the teeth 90 of the ratchet and prevent reverse movement. By having a plurality of pawls, there willalways be one of said pawls that will engage-one of the teeth of the ratchet so as to eliminate lost motion.

In the forward face of the ring 80 and disposed intermediate the recesses 82 are a plurality of annularly spaced recesses 95. With'each recess is a pawl 96 similar to the pawls 85 and urged outwardlyof the recess 95 by a'spring 97. The pawls 96-are termed drivering pawls and the teetlr'9S-thereofare adapted toengagc with teeth 99 of a drive ratchet 100 rotatably disposed on the shaft 43 and operatively positioned adjacent the ring 80. The ratchet 100 is provided with peripheral gear teeth 101 at the end remote from the ring 80 and the gear-toothed portion of said ratchet is received in a recess 104 provided therefor in a drive-gear housing 105 fixed to the wall 22 by any suitable means such as welding or the like. The housing 105 is provided with an axial opening through which the shaft 43 extends and in which said shaft rotates. The recess 104 is cut into at one side by a vertical opening 106, Fig. 8, in a lateral extension 107 of said 'housing 105. -The-opening 106 slidably receives a pedal-operated rack bar 108 having teeth 109 adapted to mesh with the peripheral gear teeth 101 of the drive ratchet 100 so that sliding movement of the rack bar 108 through the opening 106 causes rotation of the drive ratchet 100. Downward movement of the rack bar 108, as indicated by an arrow in Fig. 8, will cause counterclockwise rotation of the-drive ratchet 100 so that the teeth 99 thereof will engage at least one of the teeth 98 of the adjacent pawls 96 to effectsaid aforementioned counterclockwise rotation of the ring 80. R0- tation of the ring 80 effects'rotation of the'shaft 43 and hence corresponding rotation of the body 47 (clockwise, as viewed from the left-hand end of Fig. 2) so thatwhen the segments 68 are engaged with the left-hand threads of the screw 39 the latter will be moved -rearwardly to effect tightening of the jaws of the vise. The holding ratchet 75 will prevent counterrotation of the shaft 43 and counterrotation of the drive ratchet 100 is permitted by the teeth of the pawls 96 which have cam faces adapted to ride over the teeth 99 of the drive ratchet 100.

Means for actuating the drive ratchet 100 by foot power comprises apedal 110 pivoted at 111 in-a housing 112, said pedal being connected to the rack 108 by means of a rod 114. The pedal 110 is pivotally connected to the lower end of rod 114 as 'at115 and said pedal is urged upwardly by a spring 116 secured at one end to said pedal and at the opposite end to a pin 117 fixed to aguard 118. The guard 118 is channel shaped to protect the rod 114 and a rod 120 of the releasing mechanism, The guard is secured to the housing 112 by any suitable means and to the wall 12 of the vise by a screw 121. The releasing mechanism'comprises' a pedal pivotedin the housing 112 on the same axis as the pedal 110 and saidpedal 112 is urged upwardly by a spring in the same manner as the pedal 110.

The rod 120 is pivotally connected at its lower end to the pedal 125 and the opposite end of said rod is pivotally connected at 126 to a bell crank 127. The bell crank 127 is pivoted on a screw 128 fixed a boss 137 (see Figure 8) formed integrally on the adjacent wall of the hollow portion 20 of the fixed jaw. It is to be noted that the pivots 126 and 128 are at the upper end of the bell crank 127. A rod 130 has one end pivoted at 131 to the lower end of the bell crank 127 and has the opposite end pivoted at 132 to an car 133 on one fork of a bifurcated release cam 135. The ear 133 is at one end of its fork (see Figures 6 and 9), and the opposite ends of the forks of the bifurcated cam 135 are integrally connected by a sleeve which is pivotally mounted on a pivot bolt 136 extending transversely through opposite walls of the hollow portion 20 of said fixed jaw. A forward edge 138 of each of the forks of the cam 135 constitutes a cam surface engageable with the plate 5-8 for urging the release sleeve 51 forwardly on the body 47 when the pedal 125 is actuated downwardly. The earn 135 is returned to the position shown in Fig. 2 when the pedal 125 is raised to its normal position (not shown) by its spring. The sleeve 51 is urged toward the cam edge 138 by springs 140 which are disposed in openings 141 provided therefor in the adjacent end of the body 47 and on opposite sides of the axis thereof. The springs 140 react between the bottoms of said recesses 141 and the plate 58 to yieldingly urge the sleeve to the position shown in Fig. 2 wherein the segments are locked into operative engagement with the screw 39.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description and it is thought that it will be apparent that various changes may be made in the form, construction and arrangement of the parts of the invention and the method of operation thereof without departing from the function and scope thereof or sacrificing all of its material advantages, the embodiment hereinbefore described being merely a preferred one.

What I claim is:

1. A vise comprising: a fixed jaw member having side walls defining a hollow housing, a back wall and a front wall, the front and back Walls having horizontally aligned openings therein adjacent the top thereof and aligned openings below same; a movable-jaw-supporting bearing extending forwardly of the front wall in the plane of the upper opening therein; a movable jaw having a horizontal body slidably disposed in the upper openings in said front and back walls; a screw support at the rear of the movable-jaw body; a screw having the rear end thereof secured against rotation in said screw support and extending forwardly thereof in downwardly spaced, parallel relation to said body, said screw extending through the lower opening in the back wall; a hollow shaft in said housing and rotatably disposed in the lower opening of the front wall, the forward end of said screw being slidably receivable in said shaft; a split nut having a body provided with an axial bore therethrough for slidable reception of said screw, and an enlarged portion in the forward end in which the adjacent end of said shaft is received and secured to rotate therewith, said body having a plurality of annularly spaced axially extendingopenings in the rear thereof and a plurality of radially extending openings therein substantially square in cross section; segments radially slidable in said radial openings, said segments having the same cross-sectional shape as said radial openings and having portions of threads at the inner ends for operable engagement with the threads of the screw, there being inclined cam faces at the upper forward corners and axially extending recesses in the rear sides out of alignment with the axially extending openings in the rear of said body; a release sleeve having a bore slidably receiving said body and having an outwardly flaring cam portion merging with an enlarged-diameter portion at the rear; a Wall closing the rear of said sleeve; release pins secured to said sleeve wall, said pins extending forwardly into the axially extending openings in the rear of the split-nut body and having pointed forward ends, said' sleeve being slidable from a rear position whereat the segments are held in their inner, screw-thread-engaging position with the pins out of the axially extending recesses in said segments, to a forward position whereat said pins enter the last-mentioned recesses to move the segments out of engagement with the screw, said cam portion of the sleeve being engageable with the cam faces of the segments when the sleeve is moved rearwardly to force said segments into screw-engaging position; yielding means urging said sleeve to the rear position; means for actuating the sleeve to the forward position, said means including a foot pedal; a ratchet-and-pawl mechanism for rotating said shaft in a direction to rotate the split nut and move the movable jaw in clamping direction with respect to the fixed jaw; means for actuating the ratchet-and-pawl mechanism, said means including a foot pedal; and ratchet-and-pawl means permitting rotation of said shaft by the first-mentioned ratchet-and-pawl mechanism but preventing reverse rotation of said shaft.

2. A vise comprising: a fixed jaw member. having a back wall and a front wall, the front and back walls having horizontally aligned openings therein adjacent the top thereof and aligned openings below same; a movable jaw having a horizontal body slidably disposed in the upper openings in said front and back walls; a screw connected to said movable jaw and held against rotation, said screw being downwardly spaced, and parallel to said body, said screw extending through the lower opening in the back wall; a hollow shaft rotatably disposed in the lower opening of the front wall, the forward end of said screw being slidably receivable in said shaft; a split nut having a body provided with an axial bore therethrough for slidable reception of said screw, said body being fixed on said shaft so as to rotate therewith, said body having a plurality of annularly spaced, longitudinally extending pin-receiving openings in the rear thereof and a plurality of radially extending openings therein substantially square in cross section; segments radially slidable in said radial openings, said segments having the same cross-sectional shape as said radial openings and having portions of threads at the inner ends for operable engagement with the threads of the screw, there being inclined cam faces at the upper forward corners and axially extending recesses in the rear sides out of alignment with the longitudinally extending openings in the rear of said body when said segments engage said screw; a release sleeve having a bore slidably disposed on said body and having an outwardly flaring cam portion merging with an enlarged-diameter portion at the rear; a wall at the rear of said sleeve, release pins secured to said sleeve wall, said pins extending forwardly into the longitudinally extending openings in the rear of the splitnut body and having pointed forward ends, said sleeve being slidable from a rear position whereat the segments are held in their inner, screw-thread-engaging position with the pins out of the axially extending recesses in said segments, to a forward position whereat said pins enter the last-mentioned recesses to move the segments out of engagement with the screw, said cam portion of the sleeve being engageable with the cam faces of the segments when the sleeve is moved rearwardly to force and lock said segments into screw-engaging position; yielding means urging said sleeve to the rear position; means for actuating the sleeve to the forward position, said means including a foot pedal; a ratchet-and-pawl mechanism for rotating said shaft in a direction to rotate the split nut and move the movable jaw in clamping direction with respect to the fixed jaw; means for actuating the ratchet-and-pawl mechanism, said means including a foot pedal; and ratchet-andpawl means permitting rotation of said shaft by the firstmentioned ratchet-and-pawl mechanism but preventing reverse rotation of said shaft.

' 3'. In a vise comprising: a fixed jaw member; a movable jaw; a 'screw .secured to the movable jaw and held against 'rotation; a hollow shaft rotatably supported in axial alignment .relative to, said screw; a splitnut having abody secured tosaid shaft and provided with an axial bore therethrough for slidable reception, of said screw, saidbody havinga plurality, of annularly spaced longitudinally extending openings, in the rear thereof and a plurality of-radially.extending openings therein substantially squarein cross section; segments radially slidable in said radial openings, said segments having the same cross-sectional shape as said radial openings and having portions of threads at'the innerends for operable engagement with the threads of the screw, there being inclined cam faces at the upper forward corners and axially extending recesses in the rear sides out of alignment with the axially extending openings in the rear of said body when said segments engage said screw; a release sleeve having a'bore slidably-disposed on said body and having an outwardly flaring cam portion; a wall at the rear of said sleeve; release pins secured to said sleeve wall, said pins extending forwardly into the longitudinally extending openings in the rear of the split nut body and having pointed forward ends, said sleeve being slidable from a rear postion whereat the segments are held in their screw-thread-engaging position with the pins out of the axially extending recesses in said segments, to a forward position whereat said pins enter the last-mentioned recesses to move the segments out of engagement with the screw, said cam portion of the sleeve being engageable with the cam faces of the segments when the sleeve is moved rearwardly to force said segments into screw-engaging position; yielding means urging said sleeve to the rear position; means for actuating the sleeve to the forward position; ratchet-and-pawl mechanism for rotating said shaft in a direction to rotate the split nut and move 'the movable jaw in clamping direction with respect to the fixed jaw; means for actuating the ratchet-and-pawl mechanism; and ratchet and pawl means permitting rotation of said shaftby the firstmentioned ratchet-and-pawl' mechanism but preventing reverse rotation of said shaft. 1 I

4. In a drive mechanism: a member to be actuated; a screw connected to said member. and held against rotation; a rotatably mountedshoft; a split nut having a body secured to said shaft and. provided with an axial bore therethrough for. slidable reception of said screw, said body having a plurality of annularly spaced longitudinally extending openings in the rear thereof and a plurality of radially extendingopenings therein; segments radially slidable in said radial openings, said segments being held against rotation in said radial openings and 5. In a drive mechanism: a member to be actuated; means for actuating said member including, screw means, split-nutmeans havinga body provided with an axial bore a for operable reception of said screw means, said body having portions'ofthreads at the inner ends for operable engagementswith the threads'of the screw, there being inclined cam faces at the upper forward corners and axially extendingrecesses in the rear sides out of alignmentwith the longitudinally extending openings in the rear of saidbody; ,arelease sleeve having a bore and slidably disposed on said body, said sleeve having an annular, outwardly flaring cam portion; release pins carried by said sleeve, said pins extending forwardly into thelongitudinally extending openings in the rear of the split-nut body and having pointed forward ends, said sleeve being slidable from a rear position whereat the segments are. held in their screw-thread-engaging position with the pins out of the axially extending recesses in said segments; to a forward position whereat said pins enter;the lastmentioned recesses to move the segments out of engagement with the screw, said cam portion of ,the:sleeve being engageable with the cam faces of the segments when the sleeve is moved rearwardly to force said segmentsz, into screw-engaging position; yielding means urging said sleeve to ithezrear POSitiQ fi means for actuating the sleeve to the forward position.

having a plurality of annularly spaced longitudinally extending openings in'the rear thereof and a plurality of radially extending openings therein; segments radially slidable in said-radial openings, said segments being held against rotation in said radial openings and having portions of threads at the inner ends for operable engagement with the threads of the screw means, there being axially, extending recesses in the rear sides out of alignment with the longitudinally extending openings in the rear of said body; a release sleeve slidably disposed on said body, said sleeve having an annular, outwardly flaring cam portion; means holding said sleeve against rotation rela tive to said body; release pins carried by said sleeve, said pins extending forwardly into the longitudinally extending openings in the rear of the split-nut body and having pointed forward ends, said sleeve being slidable from a'position whereat the segments are held in their screw-thread-engaging position with the pins out of the axially extending recesses in said segments, to a position whereatsaid, pins enter the last-mentioned recesses to move thesegrnents out of engagement with the screw, said-cam portionof the sleeve being engageable with the segmentswhen the sleeve is moved to the first-mentioned position to force said segments into screw-engaging position; yielding means urging said sleeve to the firstmentioned position; and means for actuating the sleeve tothe second-mentioned position, rotation of one of said meanscausing actuation of the other means to effect actuation of said member.

- .6. In a split-nut mechanism for releasable connection with a screw: a body provided with an axial bore therethrough for slidable reception of a screw, said body havingza .plurality of annularly spaced longitudinally extending openings in the rear thereof and a plurality of radially extending openings therein; segments radially slidable in said radial openings, said segments being held against rotation in said radial openings and having portions ofthreads at the inner ends, there being inclined cam faces at the upper forward corners and axially extending recesses in the rear sides out of alignment with the longitudinally extending openings in the rear of said body; a release sleeve having a bore and slidably disposed onsaid body, said sleeve having an annular, outwardly flaring cam portion; means holding said sleeve against rotation on said body; release head pins carried by said sleeve, said pins extending slidably into the longitudinally extending openings in the rear of the splitnut body and having pointed forward ends, said sleeve being slidable from one position whereat the segments are held; in an inner position with the pins out of the axially extending recesses in said segments, to a second position whereat said pins enter the last-mentioned recesses to move the segments outwardly, said cam portion of the sleeve being engageable with the cam faces of the segments when the sleeve is moved to said one position; and yielding means urging said sleeve to said one position.

7. In a drive mechanism: a member to be actuated; means for actuating said member including, screw means, split-nut means having a body provided with an axial bore for operable reception of said screw means, said body having a plurality of annularly spaced longitudinally extending openings in the rear thereof and a plurality of radially extending openings therein; segments operably disposed for sliding movement in said radial openings and having portions of threads at the inner ends for operable engagement with the threads of the screw means; a release sleeve slidably disposed on said body, said sleevehaving a cam portion; means holding said sleeve against rotatio realtive to said body; release pins carried by said sleeve, saidpins extending forwardly into the longitudinally extending openings in the rear of the split-nut body and being engageable with said segments, said sleeve being slidable from a position whereat the segments are held in their screw-thread-engaging position with the pins out of engagement with said segments, to a position whereat said pins engage said segments to move same out of engagement with the screw, said cam portion of the sleeve being engageable with the segments when the sleeve is moved to the first-mentioned position to force said segments into screw-engaging position; yielding means urging said sleeve to the first-mentioned position; and means for actuating the sleeve to the second-mentioned position, rotation of one of said screw and split-nut means causing actuation of the other of said screw and split-nut means to effect actuation of said member.

8. In a drive mechanism: a member to be actuated; means for actuating said member including, screw means, split-nut means having a body provided with an axial bore for operable reception of said screw means, said body having a plurality of annularly spaced longitudinally extending openings in the rear thereof and a plurality of radially extending openings therein; segments radially slidable in said radial openings, said segments being held against rotation in said radial openings and having portions of threads at the inner ends for operable engagement with the threads of the screw means, there being axially extending recesses in the rear sides out of alignment with the longitudinally extending openings in the rear of said body; a release sleeve slidably disposed on said body, said sleeve having an annular, outwardly flaring cam portion; means holding said sleeve against rotation relative to said body; and release pins carried by said sleeve, said pins extending forwardly into the longitudinally extending openings in the rear of the splitnut body and having pointed forward ends, said sleeve being slidable from a position whereat the segments are held in their screw-thread-engaging position with the pins out of the axially extending recesses in said segments, to a position whereat said pins enter the lastmentioned recesses to move the segments out of engagement with the screw, said cam portion of the sleeve being engageable with the segments when the sleeve is moved to the first-mentioned position to force said segments into screw-engaging position.

References Cited in the file of this patent UNITED STATES PATENTS 249,003 Cherry Nov. 1, 1881 279,897 White June 19, 1883 950,431 Bradford Feb. 22, 1910 1,025,377 Craig May 7, 1912 2,393,764 Frank Jan. 29, 1946 FOREIGN PATENTS 16,618 Great Britain Aug. 16, 1905 

